docs: fix quotemark (#14222)

Author: Rich-Harris

packages/kit/src/types/synthetic/$env+dynamic+private.md

@@ -9,4 +9,4 @@ import { env } from '$env/dynamic/private';
 console.log(env.DEPLOYMENT_SPECIFIC_VARIABLE);
 ```
 
-> In `dev`, `$env/dynamic` always includes environment variables from `.env`. In `prod`, this behavior will depend on your adapter.
+> [!NOTE] In `dev`, `$env/dynamic` always includes environment variables from `.env`. In `prod`, this behavior will depend on your adapter.